Looking at the box art, which looks really nice by the way, Boo and Bowser Jr. look like they could be playable. Shy Guy not so much since there's two of them and the cards Luigi's holding. I think Rosalina's part of a board rather than a playable character (as seen in a trailer a while ago).

If there is a Bowser space there will probably be Bowser. This game is looking pretty good I will probably pick it up.

GamecubeloggeryForget the Nintendo seal of approval
I only see GC 4.0 happening if I become a English major. Yeah, it is happening now. GC 4.0 will be released in 2020.
My Bio by True_HeroMy Soundcloud

Honestly, unless Nintendo found some way to fix the problem of if someone you are playing with turns of their 3DS the game ends, I don't see online happening. They could just make that person become a CPU, but I somehow don't see Nintendo doing that. Mario Party takes like 40-60 minutes if you do 20 turns, so it would happen pretty often that people would have to leave, also I could see a lot of people quitting if they were losing...